Electrical measuring instrument.



PATENTED JAN. 8, 1907.

J; M LEA. ELECTRICAL MEASURING INSTRUMENT.

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APPLICATION FILED SEPT..25.190B.'

PATENTED JAN. 8,1907.

J. MQLBA. (I ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED SEPT. 25. 1903. Q

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JOHN M. LEA, oF- cmciieo, ILLINOIS, ASSIGNOR TO INTERNATIQONAL ,IEEECTRIC METER COMPANY, or CHICAGO, ILLINOIS, A .co irosa of the United States, residing at Chicago, in

' TION OF ILLINOIS.

ELECTRICAL MEASURING INSTRUMENT.

- No. senses.

To all iv/wm it may concern: Be it known that 1, JOHN M. LEA, a citizen the county of Cook and State of Illinois, have invented a certain new and useful 'Improvement in Electrical Measuring Instruments, of which the followingisa full,"'clear, concise, and exactdescription.

' My invention relates to an electric measuring instrument and its object is to provide an improved construction whereby two separate and independent instruments, such as an ammeter and a voltmeter, may be compactly mounted within the same easingpso as to occupy the minimum spaceand present a neat appearance without sacrificing accuracy, de icacy'of adjustment, or strength.

My invention also contemplates an improved mounting such that the connectingwires may all be conveniently led to the various terminals through a channel in the back plate.

I will describe my invention more particularly by reference to the accompanying drawings, in which Figure 1 a front view ofa combined ammeter and voltmeter constructed according to my plan. Fig. 2 is a vertical sectional view thereof on line 2 2 of Fig. 1. Fig. 3 is a front view of the interior mechanism, the cover and the two scale-plates having been removed; and Fig. 4 is a transverse sectional plan view on line 4 4 of Fig. 3.

The same letters of reference indicate the same parts wherever they occur.

The instrument comprises two separate and independent meter-movements,. each with its own needle and separate scale arranged in tandem within the singleinclosing case, great com actness of arrangement being made possi le by dis osin the metermovements one behind t e 0t er close together, so that their scales are in arcs lying one within the other. The needles 2) and a. may be arranged to swing in separate planes one above the other, and separate scaleplates 12 a are provided, which may be independently sup )orted, as shown, one between the lanes of t e two needles'and one underneat the lower needle. The meter-movements in the instrument illustrated are of the dArsonval type, comprising movin coils a 0 adapted to carry t e current to e meas- Specification of Letters Patent.

Application filedsepteinber 25. 190a Serial m. 336.120.

Patented Jan; 8, 1907.

t red, (or a fraction thereof,) each of said coils being pivoted to swing between the concave pole-pieces of a permanent magnet, asoftlron stationary core a or '0 being mounted centrally between'said concave pole}, 'ieces,

leaving an annular air-gap in which t e coil,

moves. I provide a single h orseshoe magnet mto furnish the magnetic field for both of the meter-movements, two, sets or pairspfi'con cave opposing pole-pieces d5 12 belngf disposed between the arms ofsaid magnet.

Each pair of pole-pieces carries a U'-sl 1'a'ped bracket 0. or v, in the upturned arms of which the pivot-pins for the moving coils are mount ed, these brackets also serving to'suppoi tgthe central soft-iron cores 0, o. Currentjisjc'onveyed to and from each-moving coil by a'pairof spiral coiled springs a a. 'v '0, which also serve to oppose the motion pf theeoil under the influence of the current. 1

The. meter-movement, composed of the pole-pieces a a ,,core,; a and the pivoted spring-mounted coil a 'carrying pointer a, 'is t e ammeter movement and is supported between the arms of the magnet m upon a bracket a which is-mounted upon a raised ridge 1* upon the back plate b of the instrument. The voltmeter-movement, composed of similar parts,is also mount ed upona bracket 4 0 between the arms of said magnet m close beside the ammeter movement, so that thetwo are in tandem arrangement.

The single horseshoe-magnet thus furnishes the magnetic field for both ammeter and volt-- meter, and the construction indicated permits of a very compact disposition of parts, I such that the ammeter and voltmeter scales may appear one immediately under the other upon the face of the instrument.

The ridge r, upon which the bracket 0. is

.mounted, is formed-by a raised portion of the the back plate and secured to the projecting channel in the rear face of the -Patent y i 1. A combined voltmeter and ammeter ends of the terminalbolts, said projecting ends of the bolts being inclosed within and protected bythe channel or recessed portion, Ihis construction Will be desirable both in switchboard instruments and portable in struments, but more particularly in iIlS'iIL1 ments intended to be used on automobiles, as the wires may be all led through a single hole .in the. dashboard, lying behind and concealed by the instrument, said wires upon emerging from the hole being led along the back plate to their respective terminal pieces,

Having thus described my invention, I claim as new and desire to secure by Letters having separate meter-movements mounted -scale-plate mounted in in tandem and indicating-needles therefor swinging inplanes one above the other, a a plane between the planes of said needles, and a separate scaleplate under the lower needle.

2. In an electric. measuring instrument,-

the combination with a base-plate having a raised portion forming a ridge upon the front face and a channel in the back, of a, metermovement and a bracket-support therefor mounted upon said ridge, electrical terminal pieces also mountedupon said ridge and exc tendin through said ridge into the channel upon the back, said channel aflording a free space for running-the wires to said terminals, in the back of the instrument.

3, In an electrical measurin instrument, the combination with a base-plate having a raised portion forming a ridge across the front face of the plate and'a channel in the back thereof, of a horseshoe-magnet resting against said ridge, a bracket mounted upon said ridge, a meter-movement supported by said bracket between the arms of said horseshoemagnet, a second bracket mounted on said base-plate and a second. metermovement supported between the arms of said magnet, in tandem with the first movement, indicating-needles for said meter-movements arranged to swing in planes one above the other, and independently-supported scaleplates over which said needles are adapted to 5c swing V In witness whereof I hereunto subscribe my. name this 15th day of September, A. D.

l J OHN M. LEA. Witnesses:

, D. C. TANNER,

i A. H. Moons. 

